


Thumbs Up

by PrinceOfHell00



Series: Sweet Devil Child [1]
Category: Kuroshitsuji | Black Butler
Genre: Adult Ciel Phantomhive, Age Regression/De-Aging, Apologetic Ciel Phantomhive, Arguing, Canon Era, Caring Ciel Phantomhive, Childhood Memories, Crying, Crying Sebastian Michaelis, Curiosity, Cute Sebastian Michaelis, Demon Sebastian Michaelis, Discovery, Emotional Hurt/Comfort, Fluff, Gen, Hiccups, Light Angst, Little!Sebastian, Loving Ciel Phantomhive, Nicknames, Non-Sexual Age Play, Platonic Kissing, Precious Sebastian Michaelis, Stuffed Toys, Thumb-sucking, Tooth-Rotting Fluff, big brother Ciel, bottle feeding
Language: English
Status: Completed
Published: 2020-08-21
Updated: 2020-10-02
Packaged: 2021-03-06 14:27:44
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 8,548
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/26020393
Author URL: https://archiveofourown.org/users/PrinceOfHell00/pseuds/PrinceOfHell00
Summary: Don't ask him when this curiosity and fascination of his started, but for a couple decades now, Sebastian has become obsessed with the human concept of "comfort objects".
Relationships: Sebastian Michaelis & Ciel Phantomhive
Series: Sweet Devil Child [1]
Series URL: https://archiveofourown.org/series/2097972
Comments: 7
Kudos: 68





	1. His Butler, Curious

**Author's Note:**

  * For [ttfan111robstar1](https://archiveofourown.org/users/ttfan111robstar1/gifts).



> This fic was requested by the lovely and talented Cloe~! I hope you love and enjoy the first chap, and look forward to the next, my friend! <3 <3
> 
> There's not much agere content in this chapter, but in the next Seb will for sure regress. ^_^

Don't ask him when this curiosity and fascination of his started, but for a couple decades now, Sebastian has become obsessed with the human concept of _"comfort objects"_. Items, or sometimes even actions, that brought humans–especially human children–a sense of safety and reassurance when in a distressed state. A blanket, a stuffed animal, or tapping one's foot repeatedly, seemed to be the most popular of choices. Sebastian couldn't understand how something so simple as tapping one's foot, or cuddling something soft, could be in any way soothing. But that's what made this particular concept so intriguing to the demon.

He dearly wanted to experiment by trying out a couple of these human methods of comfort on himself, but every time he would even attempt to, whatever Master he had at the time always seemed to need him for something or another, resulting in all of his time and attention being taken up; being in a contract, he had no choice but to follow orders when given, even when all he wished to do was feed his curiosity over the strange wonders of humanity. It wasn't until he formed a contract with Ciel Phantomhive, that he finally got the opportunities to experiment.

The first object he tried was a stuffed animal. He'd seen many small children with one, how attached they would get to the stuffed toys, and how they would cry and scream their little heads off if they were even threatened to be separated from the objects, or if the toys became lost somehow. He's also witnessed how some would stand in front of a toy shop window, and whine and beg their parents until they were red in the face to buy them one. When Funtom's annual monthly shipment of toys and candy arrived to the Phantomhive manor for testing, Sebastian discreetly snuck one of the stuffed cats (a short haired Siamese cat with ocean blue eyes) out from the box labeled, 'stuffed animal toys', and hid it in his wardrobe with the real cats he kept in there. Later that night, when he returned to his room after taking care of some amateur assassins who tried coming for his Master, Sebastian removed his gloves (to really experience the full affect of the toy) and retrieved the stuffed cat from his wardrobe. He sat upon the edge of his bed, and gave the plush creature in his hands a gentle squeeze. The toy was certainly very soft, and Sebastian could certainly see how that attribute was one of the reasons why so many children slept with one. For the rest of that night, Sebastian alternated between sitting up and petting the plush cat, to lying down on top of the bed and cuddling the toy to his chest, trying to emulate what a child would do to gain that certain comfort only a stuffed animal could supposedly provide. But alas, his experiment with stuffed animals and their supposedly soothing affects, ended with him still not entirely understanding how something stuffed with cotton and made to look like an animal could offer one comfort (though, he did keep the stuffed cat for decorative purposes).

The second object he tried was a blanket. He'd seen many children from ages three and under carry around their favored brightly or pastel colored blankets' everywhere they went–and like with a stuffed animal, they would wail their little heads off if the blanket was lost or threatened to be taken away. While out one day with the young Lord searching for a gift for Lady Elizabeth's birthday, the demon managed to sneak away for a few moments–while the Earl was distracted by the dress shop owner's overly enthusiastic speech on what would be the perfect gift for a lady of nobility–and go into the shop next door. It was a baby and toddler catered shop, where items ranging from bottles and rattles, to stuffed animals and wooden blocks were sold. He quickly sought out what he came for, knowing he only had a certain amount of time before Ciel realized his disappearance. In the center of the shop, right beside two other wooden tables of baby items, resided a table with a wicker basket full of neatly folded baby blankets (all no longer than Sebastian's forearm) sat atop. Sebastian grabbed the nearest one, it was crocheted out of wool, and the designs were a mix of white, light blue and dark blue square patterns. He ran his fingers across the coarse fabric, slightly pinching it in different areas, and looking it over from all angles, trying to come to an understanding as to why these little pieces of fabric were so appealing. After picking up and inspecting two other blankets made from two different materials, he came to the conclusion that none of them were really all that interesting or soothing to him. So in the end, just like with the stuffed animal experiment, the blanket experiment went about the same.

For awhile he gave up on the whole thing (forgoing the foot tapping, since it was a rarity for him to ever feel anxious or nervous), figuring there wasn't anything that could make him understand the comfort and joy humans received from something other than another living creature.

It wasn't until one day, when the demon was out doing an errand for his Master, that he came upon a very curious scene through the window of a restaurant, forcing him to stop and stare with intense fascination. A woman was sat at a table engaged in conversation, presumably with her husband who sat across from her, and in her lap was a child who appeared to be no older than a year old, sucking on their thumb without a care in the world. Something about that scene struck a chord in Sebastian, and it took every ounce of self-restraint he possessed not to copy the babe's action.

He'd heard about thumb-sucking many times before, of course. How almost every human baby sucked their thumb for comfort until they reached a certain age and were taught it wasn't appropriate anymore, but he never actually bared witness to it until now. It was beyond fascinating; how the simple act of sucking one's thumb could be soothing and comforting to a small human. Sebastian wanted to truly understand the reasoning behind the action, he desperately wanted to know what it was that child felt in that moment–what it must always feel like when they suck their thumb.

By the time he completed his task and returned to the manor, dusk was upon the horizon, and Sebastian couldn't help but feel a flutter of anticipation at what he would get to do once the house fell into slumber for the night.

After dismissing the five servants for the evening, and getting his Master ready for bed, then doing one final sweep of both the inside and outside of the manor, Sebastian was finally able to retreat to his chambers for the remainder of the night. Once in his room, the demon began stripping out of his uniform, planning on dressing into the one set of causal clothing he owned. For some strange reason, he felt that he needed to be dressed in something comfortable for this experiment. He opened the top drawer of his dresser, pulling out the black nightshirt and matching pajama bottoms that were gifted to him by Lady Elizabeth four Christmas' ago. This would only be the second time he wore them; the first had been the same day he received them, per the lady's bubbly insistence.

Once he was dressed in his nightwear, Sebastian lied down on top of his bed, over the covers with his head resting comfortably against the pillow. He raised his right thumb up to his lips, hesitating for only a second, before sticking the digit in his mouth and giving it a couple tentative sucks.

Sebastian's eyes widened at the instant calm that washed over him. It did feel a little bit strange having a foreign weight settled against his tongue, that brushed the roof of his mouth with every pull, but as he continued to suckle, that calmness only increased; until he fell into the most tranquil state he'd ever been in. And for the first time in his eternal life, Sebastian also felt a sense of... _safety_.

Oh. Oh!

He finally understood. One of his experiments actually succeeded, and now _he finally understood!_

The safety, the tranquility, the way it made him feel like closing his eyes and allowing himself to actually go to sleep–this had to be the greatest, most wonderful feeling anyone could experience. It certainly felt that way to him, at least.

Sebastian looked over at the clock on his wall. It was just a little after 11:30pm. He still had enough time before he had to prepare for the next day, so the man decided he could indulge himself with a few hours of sleep (thumb obviously included).

Thumb firmly lodged in his mouth, the demon turned onto his side and curled his body into a slight fetal position. He let out a content sigh, allowing his heavy eyelids to fall shut, thumb gently bobbing between his lips as he drifted off into a peaceful slumber.


	2. His Butler, Childish

**Summary for the Chapter:**

> "On any other day, Sebastian would have simply just watched the cute display with an adoring smile on his face for a few minutes, before swiftly getting back to his scheduled tasks. But for some strange reason, seeing the two kittens playing together only ended up making Sebastian frown, and feel a tiny twinge of sadness deep in his chest. It was a sudden, silly thought, but watching the cats caused the desire for a sibling of his own to bubble up from the depths of his conscious. And it wasn't long after that before his "little self" was bubbling to the surface, as well."

**Notes for the Chapter:**

> Damn writer's block was a bitch with this chapter, but it's finally complete! I'm very pleased with how it turned out. I hope you enjoy it and that it's what you had in mind, Cloe! <3

As the weeks passed by, and Sebastian's thumb-sucking became a frequent nightly ritual when he didn't have anything to do around the manor in the late hours of the night, the demon quickly took notice of how he seemed to slip into an unusual state of mind during his "downtime" in his chambers.

As the stress and responsibilities of the day would melt away, his mind would be taken over by a hazy, cloudy sensation, leaving him immensely relaxed and calm–no thoughts of anything that happened the day before, or any for what may come in the next. That hadn't been what tipped him off into examining his thoughts and behavior more closely during those nights, though. After about a week of indulging in his newly discovered, relaxing pastime, a new feeling developed. Now not only did his head become hazy and cloudy, but everything around him would feel like it was growing larger and larger, until he was left feeling like he was only half the size of his desk chair. It made him feel so... _vulnerable_ , a feeling he had never before experienced. It was a little unnerving, to say the least, but after the first couple times he experienced it, it became familiar and less unwelcomed.

He became easily distracted and extremely fascinated by the smallest of things, as well. There had been a night where he spent most of it staring at the flicking flames of the candles on his dresser, enchanted by how they danced along the wick, and how they caused the wax to slide and drip into the candle's holder–everything was always so mesmerizing in those moments.

When Sebastian went into those states, he also discovered that he wished and desired for certain items and affection that would otherwise never cross his mind. The demon actually begun using the stuffed cat on his desk as it was intended for, cuddling it and playing with it–getting genuine enjoyment from the toy–and even wishing for another so his stuffed companion (Bellamine, as he'd come to call her) wouldn't be lonely when he wasn't able to play. It was tremendously childish of him, he knew that, but he just couldn't bring himself to care or feel ashamed by any of it. Being a demon had its perks and advantages in that regard, but because of that fact, it also meant that he never got to experience what it was like having parents _or_ sibling; so during those moments of vulnerability, he couldn't help but desperately yearn for that knowledge–for the feeling of being loved and cared for by another creature.

Some nights he would imagine what it would be like to have a family to love and be loved by; a mother to sing lullabies to him and rock him to sleep, a father to play with him and read stories to him, an older sibling to look out for him and play games with him, and a younger sibling to teach things to and be annoyed by–those were the things he couldn't help but desire. With the vulnerability of those nights at their highest, and his yearning so deep and powerful, Sebastian would sometimes cry legitimate tears of heartache and sorrow for what he thought he would never have.

He sometimes wished he could tell others about this side of himself, but from what he's seen many a time, almost all of human society frowned upon childish behavior after a certain age, especially once a human reached adulthood. Sebastian didn't understand why doing something as innocent as sucking one's thumb, or cuddling a stuffed animal to sleep, was seen as immoral and disgraceful by humanity when it was an adult that did it. Humans really didn't make sense.

For those reasons, Sebastian made sure when he sucked his thumb that he was in the privacy of his chambers, or in secluded areas of the manor. He tried not to do it so often outside of his room, but sometimes the stresses of the day got to be too much for even a creature like him to handle without wanting to scream and pull out his hair, and sucking his thumb for just a few moments throughout it helped to keep him focused on whatever task he was doing. He was always very careful of when and where he did it, always making sure he kept all of his senses heightened to detect when the other servants or his Master were near by. But he should have realized sooner, that even with him being a demon, he still wouldn't be able keep this secret of his hidden forever.

Two months after his first time experiencing the blissful wonder that was thumb-sucking, and since his discovery of this vulnerable side of himself (which he started referring to as his "little self" whenever that headspace overcame him, since he never felt like his usual "big", demonic self during that time; instead feeling like nothing more than a small child)–one day while Sebastian was dusting the library and passed by one of the windows, he caught sight of two kittens (both only about a month old, he estimated) playing outside together. He stopped walking towards whatever object he'd planned on dusting next, and backtracked to stand in front of the glass panes. The kittens were siblings, he could tell by their matching jet black fur, and by the way they interacted with one another.

On any other day, Sebastian would have simply just watched the cute display with an adoring smile on his face for a few minutes, before swiftly getting back to his scheduled tasks. But for some strange reason, seeing the two kittens playing together only ended up making Sebastian frown, and feel a tiny twinge of sadness deep in his chest. It was a sudden, silly thought, but watching the cats caused the desire for a sibling of his own to bubble up from the depths of his conscious. And it wasn't long after that before his "little self" was bubbling to the surface, as well.

Before Sebastian could fully comprehend what he was doing, the demon was pulling off his left glove and sticking his thumb in his mouth, quietly sucking on it as he continued to watch the the kittens pounce and playfully nip at each other, a lugubrious expression on his usually passive face.

Sebastian didn't know how much time passed, but suddenly the sound of the library door opening pulled him from his somber thoughts. He whipped around, eyes comically wide and thumb still in his mouth.

His Master, Ciel Phantomhive, was standing in the doorway, blue eye blown wide and mouth hanging open in shock. Master and servant could only stare at one another for a prolonged amount of time in tense silence.

The part of Sebastian's brain that wasn't paralyzed by shock and terror, told him he should probably take his thumb out of his mouth, but his body refused to move. And really, even if he could, he really didn't want to give up the only thing that was currently keeping him from bursting into tears. Sebastian couldn't tell if he wanted to cry because of being startled by his Master's sudden entrance, or because said Master discovered his secret; a secret he had especially never wanted the Earl to know of.

Eventually, and with slow, deliberate movements, Ciel stepped further into the room and quietly shut the door behind him.

"What... what the hell are you doing, Sebastian?"

Surprisingly, Ciel's tone wasn't angry or disgusted, instead the man only sounded confused and vaguely intrigued.

Knowing he needed to give his Master a proper answer and explanation, Sebastian gradually began to pull himself out of the thick, foggy haze that swirled around his mind. He blinked away his tears, then begrudgingly pulled his thumb from his mouth, and slipped his glove back on.

"I apologize for appearing to you in such an indecent manner, my Lord."

Sebastian placed his hand over the left side of his chest and gave a bow.

"Sebastian, why were you sucking your thumb like a child?"

Again, the Earl's tone didn't carry anything but curiosity and bewilderment by what he'd just seen, making Sebastian feel a little less apprehensive about explaining himself. If his Master was continuing to not show any type of fury or disgust from witnessing his demonic butler suck on his thumb, then maybe telling him about this hidden side of himself wouldn't turn out to be so bad, after all.

Sebastian straightened back up and cleared his throat.

"Well, you see, my Lord–I have been alive for many moons, and because of that, I couldn't help but grow curious about the well known human concept of 'comfort objects and actions'. After I became your butler, I began experimenting with different items that supposedly soothed children. When nothing seemed to work, I gave up for quite some time on ever finding something that would make me feel what humans did, thinking there truly was nothing a creature like me could ever come to understand the simple joys and comforts of. It wasn't until two months ago, that I discovered the act of thumb-sucking and its magnificent, soothing effects."

"So, even though you're a demon, you _actually_ derive enjoyment from doing something so... innocent, and childish. Interesting."

Even though Ciel still didn't sound angry or revolted by him, Sebastian still couldn't help but be concerned a little by the now unreadable expression present on his Master's porcelain face.

"I hope I haven't offended you, Master. I know it's not appropriate for a butler to act in such a way, but I don't think I'd be able to stop unless you ordered it–and please, _please_ , my Lord, don't order it. I beg of you." Sebastian couldn't help the tiny bit of desperation that bled into his words. He couldn't fathom the thought of ever giving up his thumb–his comfort, his happiness, the only innocence he possessed–or everything else that came with it.

"Don't spin yourself into a tizzy, Sebastian, I will be doing no such thing. Honestly, I could care less what you do in your spare time alone. Just so long as you continue to properly do your job as my butler and my demon, and keep this behind closed doors and away from the public eye, you may go ahead and do whatever."

Sebastian's pleading expression turned into one of surprise at his Master's words. But had he really heard the young man correctly? Was he truly alright with Sebastian continuing to commit such an infantile act?

"Oh, don't give me that look. Contrary to popular belief by those of the business world–and I'm sure even you–but I'm not an entirely heartless person."

Ciel walked over to one of the armchairs and took a seat, elegantly crossing one leg over the other, and leaning back into the chair with his hands clasped in his lap.

"Come sit with me, Sebastian," the Earl said in a casual tone, motioning towards the sofa in front of him with his head.

"Yes, my Lord," Sebastian responded, doing as his Master said and taking a seat across from him on the emerald green sofa, though not without giving the young man a confused look as he did.

He really hoped Ciel hadn't just been messing with him when he told Sebastian the demon could do whatever he pleased in his own time, and was now about to start loudly reprehending him for his infantile act, and begin making fun of him for it, and order him to stop sucking his thumb forever, and–

"So, would you also mind explaining to me why you looked as if you were about to start crying _actual_ tears when I walked in here? Last I knew of, demons don't cry. Well, then again, I do suppose demons don't usually suck their thumb, either. Well anyway, regardless–explain."

He actually noticed that? His Master kept surprising him today.

Well, he supposed telling Ciel the other half of his secret wouldn't end too horribly. Ciel had taken the knowledge of the demon sucking his thumb way better than he had ever expected him to, so telling him about his "little side" should go about the same way. He hoped it would, at least.

"Yes, Master."

Sebastian clasped his own hands over his lap, and quietly cleared his throat again.

"A short while after I begun sucking my thumb, I began to notice that whenever I did, I would begin to exhibit behaviors like that of a child; wanting to play with toys, talking in a very childlike manner, desiring the affection of another being, and becoming easily emotional. I call this other version of myself my 'little self', since for all intents and purposes, I become a child in those moments. Everything around me will feel so much bigger and sound so much louder, and it automatically causes me to feel small and helpless–vulnerable. In my long existence, I had never felt such things before. But now I do, and I actually welcome these new feelings."

Sebastian paused a moment, taking in his Master's reaction. Besides looking a little surprised, the Earl's expression remained the same as it did when he sat down. So far so good then. He continued his explanation.

"It's usually only set off when I deliberately suck my thumb, but sometimes it can be set off by other things, as well. Like today, for instance. A while before you came in here, I got distracted by a pair of kittens play fighting outside of the window, and it caused me to revert to my little self. So when you entered the room so suddenly, I got startled at the sound of the door, and at the prospect of the less-than-pleased reaction I might end up receiving from you after discovering that other side of me. That's why I looked ready to cry."

His explanation came to an end, and he anxiously awaited his Master's response.

After a couple moments of Ciel regarding Sebastian in silence, he finally spoke.

"That's... certainly not was I was expecting to hear you say. Though, I'd be lying if I said I wasn't intrigued by this.. 'other version' of you. I never thought a demon could experience the things you mentioned."

"Neither did I, my Lord."

"It's quite astonishing, actually. I can't say that I entirely understand it all, but as I said before about the thumb-sucking, so long as you continue to do your job and keep it behind closed doors, you may do as you wish."

Sebastian couldn't help but give his Master a wide, grateful smile. "Thank you, my Lord! You have no idea how relieved I am to know you're not upset by this."

Ciel just shrugged, setting his left elbow onto the armrest and leaning his chin against his fist. "No need to thank me. Like I said, I'm not an entirely heartless person to deny someone their simple joys. It's not as if you're doing anything harmful, after all."

"Still, thank you, Master. It really does mean a lot to me."

The Earl's neutral expression softened somewhat, and he gave a tiny nod.

"So, do you think I could... meet your 'little self' sometime? I mean–only if you're comfortable, that is," Ciel nervously asked, looking away from Sebastian as a light flush dusted over his pale cheeks.

Sebastian chuckled lightheartedly. "I think I would like that very much, my Lord."

Telling Ciel about his little self really hadn't turned out bad, at all indeed.

It had been three months since Ciel discovered his butler sucking his thumb in the manor's library–plus since finding out about the demon's "little self"–and since Ciel became Sebastian's older brother-like figure whenever the demon went into his little mindset.

Four days after initially finding out about Sebastian's little side; one night after Ciel got through with the remainder of his paperwork, Sebastian let him know that it would be a "Little Night"–if the Earl was still interested in meeting his little self. That was the night Ciel had been officially introduced to Sebastian's little side. Ciel would have been lying if he said he hadn't been a bit taken aback by seeing Sebastian hold a stuffed cat to his chest (which he internally rolled his eyes at. _Of course_ the demon would own a toy like that), while he sat on the edge of his bed with a thumb jammed in his mouth, red eyes wide with childlike innocence and shyness. It was a bit bizarre to witness, but he also had to admit, Sebastian actually made quite the darling little boy.

Ciel will forever remember the conversation he and Sebastian had the night of their first meeting–leading them to their little brother/big brother relationship.

_"C-C?"_

_Sebastian called out in question, looking up from the small pile of stuffed animals he'd been playing with on the floor._

_"Hm? What is it, lad?" Ciel answered from his place on the regressed demon's bed._

_"Wha'th it like t'have a daddy an' mummy?"_

_Ciel blinked in surprise, slightly taken aback by the demon's question._

_"Oh, well, um... I can't speak for everyone else in the world, but I can tell you what it was like to have my mother and father as parents."_

_"There was never a moment where I didn't not feel loved or safe with my parents. Whether I was with my father, or my mother, or with both of them at once, I always felt secure in my place as their son. When I was frightened or sad, they would always be there to sooth my worries and fears with hugs, kisses, and comforting words. I never once had to question if they loved me or not, because every single day they proved to me that they truly did. Not only with just words either, but with actions."_

_"I have many fond memories of them, memories I can still remember so clearly." Ciel let out a wistful sigh, a faint smile ghosting over his features. "I remember when I was very young, after my father would get down with his work, he would spend the rest of the afternoon until dinnertime playing with me in the drawing room. We would play all sorts of things together, but my favorite thing to do with him was play with my stuffed animals. I would create these silly and elaborate tales, and he would always act them out with me, and would even give each of the toys voices. He always made me laugh with those voices."_

_An image of his father holding up a light blue rhino plush, and making a silly face as he spoke in a high pitched voice, flashed through his mind's eye._

_He shook away the bittersweet memory, and continued on._

_"And one of the fondest memories' I have of my mother, was that whenever I became ill or just couldn't get to sleep, she would sit by my bedside and hum to me while she carded her fingers through my hair. It never failed to put me to sleep, or to make me feel like everything would be alright. Whether she was humming or singing, her voice was the true definition of beauty. I still miss that voice dearly."_

_Another memory_ _flashed_ _through his mind, this one an image of his mother looking down at him with a tender smile, as she rocked him in her arms and sung him a lullaby._

_He cleared his throat and deliberately blinked his eyes a few times, banishing the emotion that overcame him for a moment._

_"For me, my parents meant 'love' and 'safety'. I never had anything to worry about when I was with them. They gave me everything I could ever need or want–and not just material objects, but things that really mattered. I was given comfort after a bad dream or thunderstorm, I was given bedtime stories every night, I was given kisses on my cuts and scraps, I was given what every child craves and deserves: love, care, and affection."_

_The entire time Ciel had been speaking, Sebastian had been staring up at him with childlike awe shining through his wide, red irises, completely engrossed in what the Earl was saying. It was quite the endearing sight, Ciel had to admit._

_"Wow, you had'a real ni'the daddy an' mummy, C-C." Sebastian smiled, voice coated in the same awe as his expression. "I wi'th I had'a daddy an' mummy t'give me love an' 'fection. Tha' wou' have been ni'th." His once mesmerized expression turned somber, and he began fiddling with the ear of his stuffed cat._

_In that moment, remembrance and realization dawned on Ciel. Sebastian never had parents. The demon never got to experience what it was to have a father who took the time to play with you and read stories to you, or a mother who sang you to sleep and gave your injuries kisses. Ciel may have lost his parents at a tragic young age, but he still had the memories of what it was like having them love and care for him. Yes, it was entirely unfair that he only got to have ten years worth of memories with them, but he could at least say he knew what it was like to receive a mother and father's love. Sebastian couldn't._

_That notion made his heart clench painfully, and is what spurred him on to ask the demon what he asked next._

_"Hey, Sebastian. Would you... would you like for me to be a... a father figure of sorts to you when you're like this?"_

_"Mmmm, no tha'th 'kay, C-C."_

_Ciel couldn't help but feel a little hurt by the outright rejection. He knew wasn't the most outwardly affectionate kind of person, but he thought he could at least give being a father of sorts a try. Nonetheless though, he would respect Sebastian's wishes._

_"Oh, well alright. That's fine, I was only wondering si–"_

_"Will you be my big bro'ver 'th'ead?" Sebastian asked, looking up from his stuffed toy and staring into Ciel's eyes with a hopeful expression._

_After a brief moment of disbelief and stunned silence, a genuine smile blossomed across Ciel's face._

_"Yes, I'd like that very much. I'll gladly be your big brother."_

After their successful first meeting–the night ending with Ciel tucking Sebastian into bed, after an hour spent playing with the regressed demon–Ciel continued to visit, play, and care for him over the next couple of weeks whenever the other man went into his little mindset. Ciel truly did enjoy taking care of his demonic "little brother", it gave him something to genuinely look forward to every other night (or day, depending on Sebastian's mental stability), and Ciel wouldn't trade that for anything.

Though, that didn't mean Sebastian was always easy to care for.

It was a (surprisingly) quiet day at the Phantomhive manor, chirping birds being the only sound within the vicinity.

Sebastian watched out of the corner of his eye as Ciel let out a heavy sigh, and reached his free hand (that wasn't holding a pen in a death grip) up to rub his temples.

"Oh, for God's sake. Why would anyone think _this_ was a good suggestion? Absolute idiocy," Ciel muttered bitterly to himself, marking a sharp X onto the signature line of the "idiotic document" lying in front of him.

For the past week, the Earl had been bombarded by stacks on stacks of paperwork, along with attending three hour long meetings _twice_ a day. To say he was stressed, would be a gross understatement.

Sebastian stopped dusting for a moment, and turned to look at Ciel. "My Lord, perhaps I can be of assistance with your paperwork?"

"As I told you yesterday, I'm fine on my own, Sebastian. Tomorrow's Saturday anyway, so I just have to get all this done today, and I won't have to worry about anything more until next week," Ciel replied, not looking up from his desk.

"Well, if you change your mind, I'm here. I have no issue in assisting you with any task that is troubling you, my Lord."

"Yes, yes, alright," Ciel murmured distractedly.

Sebastian just gave a quiet sigh and got back to dusting. His Master was truly one of the most stubborn humans Sebastian has ever known.

The room returned to silence, both Master and servant continuing their respective tasks. That silence didn't last long, though.

Both men flinched when the door to the Earl's office abruptly slammed open, looking over to see who so rudely entered without knocking.

The Phantomhive gardener, Finnian, stood in the doorway, expression heavy with concern as he trained his teary gaze on the man behind the mahogany desk.

Ciel shot up from his desk, his single blue eye blazing with fury. "Finny! What have I told you about–"

"I'm so sorry, Master! But I had to speak with you right away!" The blond-haired man bowed deeply.

Ciel shut his eye for a moment, and exhaled a breath of annoyance. "Fine. Stand up and get on with it then," he said, sitting back down.

Finny hastily straightened up. "While I was in the garden trimming the roses, I found four kittens. They look like they're only a few weeks old, and it seems like their mother hasn't been around, because they look like they haven't eaten in a couple days. What should we do, Master?"

Ciel fixed the gardener with a glare. " _This,_ is why you decided to barge into my study and interrupt my work? For God's sake, I don't have time to waste with such nonsense." Ciel turned his head to look at Sebastian. "You'll take care of this as soon as you get done with the cleaning. Understood?"

Sebastian's face lit up at Ciel's words, lips splitting into a wide grin. He was going to get to nurse four– _four_ kittens back to health! Maybe he could even convince Ciel into letting him keep one.

"Yes, C–Master. Yes, Master. I'll get right on it as soon as I'm done here." Whoops. Hopefully the other two men in the room didn't notice his word slip up.

In his excitement about the kittens, Sebastian hadn't noticed he slipped into his little mindset. It had been awhile since his last regression, given how busy Ciel has been. He probably should have at least taken a night or two to regress on his own, but he'd gotten so used to having Ciel there with him, that it never felt right to do it without the man present. If he did regress on his own, it would be like it did before Ciel found out about his secret. Lonely. Sebastian hated that feeling.

Luckily, the demon didn't feel too young at the moment (maybe six?), so he'd be able to hide it until Finny left. He might even be able to persuade his big brother into playing with him after the man got through with his work (Ciel _had_ said he wouldn't have anything to worry about over the weekend, after all).

Ciel gave him a short nod, before turning back to Finny. "You may continue on with your duties–without any further interruptions, might I add. Sebastian will see to it that the cats are disposed of."

Sebastian's heart sank when he heard those words, smile instantly falling.

What did Ciel mean by those words? He... he couldn't possibly be implying... No, wouldn't... No! He couldn't make Sebastian do something so horrible like that, they were just innocent, helpless kittens! Why would Ciel want him to do something so cruel? They were just kittens in need of some care–which Sebastian could easily provide! They were–

"Sebastian!"

Sebastian jumped and whipped his head over to Ciel, realizing he got so caught up in his tumultuous thoughts, that he hadn't heard Ciel calling his name multiple times. He glanced out of the corner of his eye to where Finny had stood, and saw that the gardener was no longer present. Good, now Sebastian didn't have to pretend to be big anymore, and he could get to the bottom of what exactly Ciel meant about the "disposing" of the kittens.

"Are you paying attention now?"

Sebastian nodded, opening his mouth to ask about the kittens. Before he could, though, Ciel spoke up.

"I changed my mind, go dispose of the cats in the garden now. Lest the others see them and decide to come barging in here to alert me, as well. You can finish cleaning the manor afterward," Ciel said offhandedly, going back to reading the documents laid before him.

"No."

Ciel snapped back in his chair, and gave the demon a blazing stare. "What did you just say?"

"No. I won't hurt them," Sebastian stated firmly.

"Sebastian, you _will_ do as you're told. From what Finny was saying, it sounds like they're already dying, so it doesn't matter now."

Sebastian pouted and narrowed his eyes at Ciel. "I don't like you, Mister." He stuck his thumb in his mouth, continuing to glare at the man.

"Well, go on ahead and dislike me then. Now get that thumb out of your mouth this instant, and do as you're told, Sebastian!"

"No, you can'd tell me wha' t'do!" Sebastian exclaimed around his thumb.

As soon as the words left his mouth, horrifying, heart dropping realization struck him. Ciel _could_ tell him what to do. Even though their relationship evolved into more than just Master and servant, they still technically had a standing contract, and Sebastian was obligated to follow any and all of Ciel's commands. And in this case, that would mean Ciel commanding Sebastian to hurt and get rid of the kittens.

Tears streamed down the regressed demon's face, followed by deep, shuddering sobs. "I-I d-d-don' wanna h-h-hu-hur'd 'eeeem!" He wailed, before collapsing to his knees.

As he continued to cry, Sebastian felt himself becoming littler and littler by the second, causing his mind to harshly descend into a deeper, fuzzier fog; resulting in his cries becoming deep and guttural, and making it difficult for him to nurse his thumb for comfort.

Before he knew it, Sebastian felt a pair of long, slim arms wrap around his shoulders and pull him against a firm chest. Sebastian burrowed his face into the neck of his older brother, one hand clutching the back of the man's blue overcoat, while he was still trying to nurse his thumb with the other.

"Shhhh, it's alright, Seb, it's alright. I'm sorry I got so angry and snapped at you like that, I shouldn't have done that," Ciel murmured near Sebastian's ear, slightly nuzzling the side of his head and pulling the regressed demon tighter against him.

"D-don' wanna hu-hur'd ki-k-ki'eeths!"

"It's alright, I won't make you do that, Seb," Ciel reassured, rubbing Sebastian's back in large circles.

"P-p'omithe?"

"I promise. That was a cruel thing of me to tell you to do, even for me. It's been a very hard, long week for big brother, so I allowed frustration and exhaustion to get the better of me. I'm truly sorry, Sebastian," Ciel said, voice heavy with guilt and regret.

Sebastian sniffled wetly, sobs gradually lessening from Ciel's words. "F-f'give you. Bu' no th'ay 'gain. W-was mean."

"I know, it was very mean, and I'll never tell you to do something like that again."

Ciel kept up rubbing Sebastian's back until his tears dried up, and his sobs turned into post-cry hiccups.

Sebastian pulled out of Ciel's arms, pulling his thumb out of his mouth to speak. "C-C, c'n–" a hiccup escaped him–"C'n I hel'b ki'eeths ge'd be'dder? P'eathe, C-C?" He gave Ciel a pleading look, red eyes wide and shimmering, and bottom lip jutted out.

Ciel looked hesitant, looking about ready to give an automatic 'no'. But in the end (like Sebastian deviously knew would happen), a resigned sigh left him, and he gave a nod.

"Yes, you may care for them until they're healthy and old enough to be found a home."

"C'nnnn I keep one, too?"

"Seb, you know I'm not fond of cats. The last thing I need is to find claw marks permanently embedded into the wood around the manor, or find cat fur on every fabric covered surface."

It looked like Sebastian was going to have to use the "Guilt Trip" tactic.

"Bu' you no'd as 'lergic no more–" another hiccup escaped him–"Annnn' you was mean an' made me th'ad. I th'ill feel th'ad, too." Sebastian pushed his lower lip out further, angling his head slightly downward so he was peering up at the man.

Ciel gave him a mock glare. "You're a manipulative little devil, you know that?"

Sebastian giggled, his pout breaking. "I know."

Ciel rolled his eyes and lightly flicked Sebastian's nose, earning another giggle from the little boy. "Fine. You can keep _one_ , but that is all. You be will solely responsible for feeding it, keeping it clean, and making sure it doesn't wreck havoc around the manor. Understood?" Ciel gave him a stern, but not unkind look.

Sebastian's lips spread into a bright grin, and he threw his arms around his brother's neck and pulled him into a tight hug. "Ye'th, ye'th! I p'omithe I take good care'a the ki'ee! T'ank you, big bro'ver!"

"Seb... can't... breathe...!"

Sebastian pulled back and loosened his grip, smile turning sheepish.

"Th'orry, C-C."

Ciel just shook his head fondly, giving the little boy a small smile. "It's alright, I'm fine now. And you're very welcome. I'm happy to hear you'll be a responsible big boy about this." If possible, Sebastian beamed even brighter at his brother's words.

The man pulled out a white handkerchief from his breast pocket, and wiped away the leftover tears on Sebastian's cheeks. "Do you think you can be big again? Or not yet? It's okay if you can't right now, I won't be upset. You can always stay here with me until I finish my work, then we can go back to your room afterward."

"Too lil'. 'Tay wi't you, p'eathe."

"In that case–" His brother tucked the cloth back into his pocket, then stood up from the floor and grabbed Sebastian's hands, pulling the little boy to his own feet–"Go have a seat on the sofa. I'm going to go tell Finny to gather the cats and put them into a box in your wardrobe for now, alright?"

"Mhm." Sebastian nodded, still smiling as he walked over to the navy sofa and plopped down onto it.

"I'll also be grabbing a few of your little things while I'm down there, so you won't be bored while I work. Is there anything in particular that you would like for me to bring up?"

Sebastian took off his right glove and stuck his thumb back in his mouth, sucking it as he thought of what he wanted. "Mmmm... Bella an' baba, p'eathe," he replied around the digit.

"Alright then, I'll be right back with Bellamine and your bottle as quick as can." With that, Ciel left the study.

While Ciel was downstairs, Sebastian kept himself occupied by sucking his thumb and twirling a long strand of his raven hair, while his mind wandered to what the kitties would look like and what names he would give them.

By the time he came up with the fourth and final kitty's name (Shadow–only if it was a pure black one, though), the door to the study opened and Ciel walked in, arms full with Sebastian's requested items, plus a couple others. Among the bottle and his beloved stuffie, there was another one of his stuffie friend's (a beige teddy bear named Almond) and his white, cotton blankie.

Sebastian took his thumb out of his mouth, making grabby hands towards Bellamine and the bottle of milk.

"Here you are, lad." His big brother handed over Bellamine and his bottle, setting his teddy and blankie beside him on the sofa. "I thought you and Bellamine could use an extra friend to play with, so I brought Almond along, too. And if you get tired, the three of you can cuddle up with your blankie for a nice nap."

Sebastian shook his head. "No nap. No'd l'eepy."

Ciel chuckled. "I said only _'if'_ you get sleepy, lad." Ciel walked back over to his desk. "I'm going to get back to work, Seb, so you go ahead and play."

"C-C?" Sebastian called out to his older brother before the man could sit down.

"Yes, Seb?"

"Give?" The little boy asked, holding out the warm bottle toward his big brother.

"You want me to feed you your bottle?"

Sebastian nodded. "Ye'th, p'eathe."

"I really do have to get back to work, Seb. May I feed you another one later this evening?"

Sebastian widened his eyes and poked out his lower lip in another pout. "P'eeeeathe?"

Ciel's expression became conflicted, fingers tapping the top of his chair as he contemplated what decision to make. After only a moment, the man stopped his tapping and let out a sigh.

"You know, for someone who says he hates dogs, you certainly know how to give a perfect 'puppy dog' expression." Ciel walked back over to him. "Alright, alright. I'll feed you, but then I have to get back to work right after, okay?"

Sebastian grinned. " 'Kay!"

"First, let's get you a bit more comfortable," Ciel said, taking a seat to the regressed demon's right.

Ciel undressed Sebastian down to his dress shirt and trousers, neatly placing his tailcoat, vest, gloves and other accessories on one of the chairs from across the sofa. Once that was done, Ciel had Sebastian lie his head on his lap, then he grasped the glass bottle in his left hand, and pressed the rubber teat to Sebastian's lips. Sebastian latched on, exhaling a soft, content sigh through his nose when the first wave of cinnamon flavored milk hit his tongue. Ever since his first bottle, he fell in love with the taste of cinnamon and milk.

Sebastian had an arm wrapped around his stuffed kitten, cuddling it close to his chest, while his other hand lightly gripped his big brother's jacket, kneading the material between his thumb and forefinger. Not long after he began suckling from the bottle, he felt a hand start running through his hair in a gentle, languid manner. Sebastian loved bottle feedings, it was a time where he could bask in the soft, warm love and affection Ciel gave him in these moments.

When the milk was only halfway drained, Sebastian was hit by a wave of sleepiness, causing his eyes to begin to flutter. The sweet warmth of the milk, combined with the rhythmic sucking motion, almost always managed to lull him to sleep during bottle feedings.

"Close your eyes and go to sleep, little brother," Ciel whispered, beginning to lightly message Sebastian's scalp.

Sebastian whined, forcing his eyes back open and tightening his grip on Ciel's jacket. He wanted to finish off the whole bottle, that way Ciel would stay with him like this just a little while longer.

Ciel gently shushed him. "It's alright, I won't get up until you fall asleep, I promise."

Instead of having a relaxing effect, those words only caused the little boy to whine louder and for his eyes to fill with tears. He didn't want his big brother to leave him all alone on the sofa. Yes, he had Bellamine and Almond for company, but it wasn't the same as having his warm, loving brother there. If he wasn't feeling so little (even littler now than before, he realized), or had a bottle in his mouth, he would have voiced all of that out loud to Ciel. But at the moment, all he could do was whimper and allow a few tears to slip free.

"Oh, Seb." Ciel stopped his ministrations on the little boy's hair and scalp, just for a moment to brush away his tears. "Don't cry, lad."

The weepy boy let out a high pitched whine when the man pulled the unfinished bottle away.

"Shh-shh-shh, it's alright, Seb, it's alright."

"No gooo!" Sebastian whined pitifully, voiced choked up, with sobs not too far off.

"I'm here, I'm not going anywhere," Ciel said, starting to run his hand through Sebastian's raven locks again, while using his now free hand to wipe away the fresh fallen tears from his face. "I'll stay with you for the rest of the day. How does that sound, lad?"

Sebastian sniffled, followed by a hiccup that made his upper body bounce. "N-no 'ork? 'Tay wi't me?"

Ciel gave him that special smile that was only meant for him; the one that made Ciel's blue eye sparkle with love and kindness, and that always engulfed Sebastian's chest in warmth.

"Yes, I'll stay with you. I've done more than enough this week to afford an early start to the weekend. Everything I have left to do can wait till Monday."

The man leaned down and pressed a kiss to Sebastian's forehead, then one to his nose, earning Ciel a happy giggle from the regressed demon.

"Now, I think it's time for a certain little devil to take his nap. And don't worry, I'll be right here when you wake up."

Just the mention of sleep had Sebastian yawning and his eyes drooping. " 'Kay, C-C," he mumbled, before stuffing his thumb in his mouth, and curling onto his side and pressing his face against his brother's belly.

Ciel draped the little boy's blankie over his shoulders. "Sleep well, little brother."

With those hushed words spoken, Sebastian's eyes fell shut, and he allowed the soothing hand in his hair and the familiar comfort of his thumb, lull him into a peaceful rest.

**Notes for the Chapter:**

> I think writing this ending gave me both diabetes AND more cavities lmao. X3  
> 

**Author's Note:**

> Please leave a comment *cough*theygivemelifeandmotivation*cough* and/or kudos if you enjoyed, and may you have a great day or night! ^_^
> 
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